Proteinase inhibitors in human synovial fluid

Abstract

Two distinct proteinase inhibitors were detected in human synovial fluid. The two inhibitors were immunologically identical to scrum α 1- antitrypsin and α 2- macroglobulin . In about 25% of patients with various joint diseases, the α 2- macroglobulin inhibitor was found inactive in the synovial fluid though active in their sera. The inactive form of α 2- macroglobulin reacted immunologically with monospecific antibody to serum α 2- macroglobulin . About 60% of osteoarthritic patients lacked the α 2- macroglobulin inhibitory activity. The possibility that enzymatic degradation of articular cartilage is enhanced due to the inactivation of certain proteinase inhibitors, and the possible role of proteinase inhibitors in the pathogenesis of joint diseases are discussed in the light of the reported findings.